Australasian Hyriidae produce larvae, called glochidia, which are parasitic on fishes. Gravid females were collected from Goodga River, south-western Australia in December 2023 and monitored for glochidial release. Glochidia were released in amorphous mucous conglutinates. A sample of conglutinate was examined under light microscopy to confirm at least some glochidia were mature, exhibiting a ‘blinking’ behaviour. Light microscopy also revealed that individuals had clearly apparent larval threads. Glochidia were examined under scanning electron microscopy. Glochidia measured 293 μm ± 1.31 SE in length, 241 μm ± 1.08 SE in height and 207.4 μm ± 0.93 SE in hinge length. The shell shape is subtriangular isosceles, with an angle of obliquity (i.e., position of the ventral apex relative to the mid-point of the dorsal hinge line) of 19.4° ± 0.32 SE and shells have s-shaped hooks lacking microstylets, each terminating to a singular point on opposing valves. The observed positioning of freshwater mussels near the upstream end of a fish ladder in Goodga River suggests a potential localised optimisation of glochidial contact with upstream-migrating host fishes, but whether this observation has enhanced recruitment remains to be tested.